If you want, the original ANACS negatives still exist. Not sure of condition. The museum (not library) staff might be able to access them for you...
Lets hope that it has stopped toning. It appears to be attractive secondary toning after a dip which wasn't stabilized (probably in the late 70's). How was it stored between the ANACS picture and being put into PCGS plastic? It is really cool to have this image history and see how much the coin has changed over the last 40 years.
That's what's on my mind as well. I bought it in 1992. It was in a flip like I believe were used with these in 1980. It stayed in that holder until 2006 when it went to PCGS.
If it has been in PCGS plastic since 2006, that has apparently not stopped the toning. There's been a big change between your 2006 pics and your 2018 pics.